Submarine telecommunications cables installed in shallow water or near-shore locations frequently must be buried beneath the ocean floor in order to avoid their exposure to towed fishing nets, anchors or other mechanisms which might damage the cable in a physical encounter. To install buried cable, towed cable-burying sleds equipped with bottom-penetrating plowshares are used to position the cable a few feet into the ocean bed at such locations.
The geologic makeup of ocean bottoms varies in density, hardness and compactability, and include non-cohesive sand and gravel, loose boulders, cohesively clay solid limestone and even harder materials such as rock. The cable-burying plowshares, therefore, must be stable, durable, easy to maintain, capable of passing the cable and possibly repeaters, and not be susceptible to snagging. Plowshares of the prior art do not perform according to these requirements in many circumstances, occasioning damaged apparatus and costly losses of burying time.
Experience with cable burying also has driven submarine cable installing companies to making plowability assessment surveys prior to committing the burying apparatus to a particular route. However, apparatus with a full range of useful features which can provide a cost-effective survey and successfully make the required soil assessments is not currently available. These include rapid deployability, fast travel along the candidate burial route, and the ability to accurately assess the route's soil conditions. In order that the survey be realistic, the apparatus must also replicate many of the functions of the actual cable burying sled. That is, the overall apparatus must be towable robust and without tipping; and the plowshare must be durable and able to respond to various soil conditions encountered in a manner in which the actual cable burial plowshare would respond. The ideal plowshare should have equal utility in both the survey and the actual burial application, without substantial modification.